The present invention relates to a power tool, in particular a right-angle grinder, having an elongated motor housing in which an electric motor is received, having a gear drive housing at a first end of the motor housing to receive a gear drive for driving a working spindle, having a handle element which is fastened rotatably at a second end of the motor housing and in which a grip switch is arranged, and having air intake slots to cool the electric motor.
A power tool of this kind that is configured as a right-angle grinder is known from the brochure xe2x80x9cFEIN Elektrowerkzeuge 1997/98xe2x80x9d[FEIN power tools 1997/98] of the applicant, and is marketed under the designation MSfa666.
Right-angle grinders of this kind are common in the form of so-called two-handed right-angle grinders; the handle element, in which a grip switch with a switch button for activating the motor is provided, is grasped with a rear hand, and an additional handle that is configured as a rod handle is held by a front hand. In right-angle grinders of this kind, the fan of the electric motor draws in cooling air through air intake slots that are located in the handle element in the immediate vicinity of the grip switch. This cooling air flows through the electric motor and emerges from the device again through suitable air outlet slots in the region of the gear drive head.
Since right-angle grinders of this kind must often be used for rough work in highly contaminated environments, there exists a risk that dust particles, chips, or the like may be drawn in through the air intake slots of the handle element, possibly resulting in damage to the power tool or at least to an adverse effect on its service life. For example, drawn-in dirt particles can, over time, adversely affect the functionality of the grip switch provided in the handle element, or contaminate the electric motor or even adversely affect its functionality.
It is an object of the invention to improve a power tool of the kind cited initially in such a way that the risk of contamination of the power tool is reduced.
It is a second object of the invention to provide an electric power tool having improved cooling characteristics. It is a third object of the invention to provide an electric power tool having improved operating reliability.
In a power tool of the kind cited initially, these and other objects are achieved according to the present invention in that the air intake slots are arranged at the second end of the motor housing.
The object of the invention is completely achieved in this fashion. Since the air intake slots are no longer arranged, as in the case of conventional power tools, in the region of the grip switch, contamination of the grip switch and thus any adverse effect on the functionality thereof are prevented. This is additionally assisted by the fact that according to a further embodiment of the invention, means for sealing the motor housing are provided at its second end opposite the handle element.
In an additional development of the invention, the handle part is arranged rotatably with respect to the motor housing. A feature of this kind, known per se in the existing art (cf. DE 195 46 328 A1), makes it possible, for example in the case of a right-angle grinder, for a particularly ergonomic posture to be assumed for both rough grinding and cutoff grinding. Especially if a rotatable handle element of this kind is provided, the arrangement according to the present invention of the air intake slotsxe2x80x94outside the handle element in the motor housingxe2x80x94is of particular advantage, since otherwise drawn-in dirt particles could severely contaminate the rotation mechanism and make the handle element difficult to rotate with respect to the motor housing.
According to another embodiment of the invention, the object is achieved, in a power tool of the kind cited initially, in that at least one baffle plate is provided for particle deposition in the flow region of the air intake slots.
The object of the invention is completely achieved in this fashion as well. Specifically, according to the present invention the arrangement of at least one baffle plate immediately in the flow region of the air intake slots results in a deposition of dirt particles, chips, and other contaminants immediately in the air intake region, thus greatly reducing the penetration of impurities into the sensitive areas of the power tool.
If an embodiment of this kind is additionally combined with the features explained previously, i.e. if the air intake slots are arranged at the second end of the motor housing, then at the same time the risk of contamination for the grip switch provided in the handle element is also reduced.
In an additional development of the invention, the baffle plate is configured as a cooling panel for cooling electronic components.
With this feature the impact panel is used in two ways, namely on the one hand for the deposition of dirt particles and other contaminants, and on the other hand to cool electronic components. This results in particularly favorable heat dissipation from electronic components provided in the power tool, and thus in greater operating reliability thereof.
In an advantageous development of the invention, air intake slots are provided at two mutually opposite sides of the motor housing, an insert element being provided, having a baseplate which extends substantially over the cross section of the motor housing and on whose respective sides facing toward the air intake slots an baffle plate is provided.
The advantage of this feature is that a larger cross section for drawing in cooling air is available, and at the same time the insert element guarantees a favorable installation capability for electronic components in the cooling air region.
In an additional development of the invention, the motor housing has, at its end face facing toward the handle element, a circular leadthrough, for the passage of cables to the handle element, that is covered by the baseplate of the insert element, a sealing element for air sealing being provided inside the leadthrough.
This feature guarantees sealing of the motor housing with respect to the handle element even if the latter is received rotatably on the motor housing. A seal of this kind prevents the penetration of dust and other dirt particles into the region of the grip switch located in the handle element, thus enhancing its operating reliability.
According to a further embodiment of the invention, the motor housing has a front and a rear motor housing part, the rear motor housing part containing the air intake slots and the at least one baffle plate.
This feature considerably simplifies the design and assembly of the power tool.
It is understood that the features of the invention mentioned above and those yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or in isolation, without leaving the context of the invention.